1. Technical Field
Embodiments of the subject matter disclosed herein generally relate to methods and systems and, more particularly, to mechanisms and techniques for electrically connecting various internal parts of a turbomachinery to an external connection.
2. Discussion of the Background
During the past years, the importance of turbomachines in various industries has increased. A turbomachine is a compressor, expander, turbine, pump, etc. or a combination of them. The turbomachines are used in engines, turbines, power generation, cryogenic applications, oil and gas, petrochemical applications, etc. Thus, there is a need for improving the efficiency of the turbomachines.
One turbomachine often used in the industry includes a compressor driven by an electrical motor. Such a turbomachine may be employed, e.g., for recovering methane, natural gas, and/or liquefied natural gas (LNG). The recovery of such gasses would reduce emissions and reduce flare operations during the loading of LNG onto ships. Other uses of this kind of turbomachine are known in the art and not discussed here. However, it is noted that a shut down of such a machine is expensive as the entire process in which the machine is involved needs to be stopped. The shut down time of the machine depends, among other things, on how quick the internal parts of the compressor can be disassembly for obtaining access to the failed part. A compressor having magnetic bearings and being housed together with an electrical motor require free access to a space between the two machines for disconnecting an electrical cable from the magnetic bearings. This is undesirable as discussed next.
An example of such a turbomachine is shown in FIG. 1. The turbomachine 10 includes an electrical motor 12 connected to a compressor 14. The connection between the two machine shafts is achieved by a mechanical joint 16. The motor external casing 17 may be attached to the compressor external casing 19 by, for example, bolts 18. The compressor 14 may include one or more impellers 20 attached to a compressor shaft 22. The compressor shaft 22 is configured to rotate around a longitudinal axis X. The rotation of the compressor shaft 22 is enhanced by using magnetic bearings 24a and 24b at both ends of the compressor shaft.
However, the magnetic bearings 24a and 24b need a supply of electrical power in order to function. The electrical power is supplied to the magnetic bearings via cables 26 and 27. Cable 26 connects to the magnetic bearing 24a while cable 27 connects to the magnetic bearing 24b. Cable 26 is provided with a head 28 that is configured to mate with a corresponding head 30 of an external electrical cable 32. Cable 27 connects in a similar way to an external cable 33. Cables 26 and 27 are exposed to the media that is processed by the compressor. This media may be corrosive and likely to have a high pressure. Thus, specific precautions need to be taken for protecting the cables. Cables 26 and 27 may be attached to an internal wall of the compressor casing 19. The same is true for the motor 12, in which cables 40 and 42 connect magnetic bearings 44 of the motor to an outside power source.
A problem with such an arrangement is the following. When assembling or disassembling the turbomachine 10, personnel needs to connect or disconnect cable 26 from the magnetic bearing 24a in order to be able to remove the compressor 14. This step is performed by opening a hatch 40 so that a person could enter, partially or totally, into the turbomachine 10 and disconnect the cable 26 from the magnetic bearing 24a. The same operations need to be performed when removing the motor. These operations slow down the entire assembly or disassembly process, which is costly. Also, this method requires extra space in the design of the compressor so that the external hatch 40 is accommodated. Another problem is that to provide the necessary space to make the hatch 40 in the housing, it is required to have enough space, therefore the housing itself and the rotor need to be long enough. However, this increase in the casing and rotors generate rotordynamic and balancing issues, therefore increasing design and budding costs and the dimensions of the whole machine. Still another problem is that it is required to provide seals to dose the hatch 40, particularly important when the working gas is an acid. Yet another problem is that it is possible to test the electrical connections between the cables 26, 27 to the bearings 24a, 24b only when the compressor 14 is installed inside the housing 19.
Accordingly, it would be desirable to provide systems and methods that reduce a time for assembling or disassembling the turbomachine.